Motor vehicles with a stop-start control system for automatically stopping and starting an internal combustion engine used to provide motive power for the motor vehicle. The stop-start systems may automatically stop the engine based partially upon driver actions, such as brake pedal actuation and accelerator pedal actuation. Furthermore, these type of stop-start systems are used reduce engine fuel consumption and engine emissions. Specifically, different driver actions may be used to affect stopping and starting of the engine depending upon whether the system is applied to a manual transmission or an automatic transmission. In the case of a manual transmission two common control modes are often referred to as “stop in-gear” and “stop in neutral.”
In some circumstances, a driver ‘change of mind’ may occur during the period following a decision to stop the engine but before the engine has actually stopped and is rotating at 0 revolutions per minute (RPM). A change of mind may result from an unexpected change in traffic conditions or because the driver has inadvertently changed the state of one or more driver operable control devices such that the system logic acts to re-start the engine. In a ‘change of mind’ event it may be desirable to re-start the engine of a vehicle equipped with stop-start technology in a short period of time (e.g., minimum amount of time possible). In order to re-start the engine in this scenario, a starter motor component may be engaged with a ring gear before the latter has completely stopped rotating in order to reduce the delay in restarting the engine. However, there may be a small range of engine speed where the starter motor can be engaged without damage occurring to the starter motor or ring gear. Additionally, engagement of the starter motor when the engine is rotating in a reverse direction may be inhibited due to the high probability of damage occurring.
The speed profile of a stopping engine may be highly non-linear and that the instantaneous acceleration of the crankshaft can be such that the instantaneous speed can vary during the starter motor component travel time by a similar order of magnitude to the range of permitted speeds for starter engagement. To engage the starter motor component at the correct speed is therefore a significant challenge. One attempt overcome this challenge is to wait until the engine speed has reached zero before the engine starter motor is engaged. However, this will delay engine starting that may be needed by the driver to enable subsequent manoeuvring of the vehicle in traffic, away from hazards, etc. This not only impacts vehicle performance but may also decrease vehicle safety.
As such in one approach, a method of controlling the stopping and starting of an engine is provided. The method includes initiating an engine shut-down and closing a throttle valve in an inlet manifold of the engine when an engine shut-down is signalled. The method further includes using a starter device to restart the engine during the shut-down if starting is signalled, the engine speed is within predefined upper and lower limits, and an absolute pressure in the inlet manifold of the engine is below a predefined limit.
In this way, the engine may be quickly restarted after a “change of mind” event occurs while decreasing the likelihood of engine damage by using both an engine speed range and inlet manifold pressure as restart triggers. It will be particularly appreciated that when both engine speed and manifold pressure are used as safe restart indicator, the likelihood of damage to the starter motor is greatly reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.